In Touch: The Ridgway's rail
Captive breeding has helped this bird rebound. Plus news of the week
The sky is a slate gray and there is a chill in the air, despite the calendar showing that it is well into June. I am driving into work, passing over the single-lane roadway that traverses the estuary and connects the island where I work with the mainland, when a bird about the size of a chicken and the color of a ripe peach rushes across the roadway. A moment later, another one of these birds follows, scurrying on his long, marsh-wading legs.
It’s a good thing that I was minding the 15 mph speed limit and avoided hitting these birds. They are Ridgway’s rails, and since 1970 they have been federally listed as Endangered.
The Ridgway’s rail had been considered a subspecies (Rallus longirostris levipes) of the clapper rail, which is found along the coasts of the eastern U.S., the Gulf of Mexico, and Caribbean islands. As a subspecies, they had been called the light-footed clapper rail, but since around 2014, when they were designated as a separate species, the bird is now called the Ridgway’s rail, with a new scientific name, too (Rallus obsoletes). They look a lot like clapper rails, and like clapper rails they make a distinctive kek, kek, kek call when they are mating or otherwise excited
As they are shy and secretive, it is rare to see one, let alone two. I used to be a fairly active birder and visited the Tijuana estuary where there are a good number of rails, and it took several years of birding at that spot before I saw one in the marsh.
Ridgway’s rails live in coastal salt marshes and lagoons, making their nests in tall, dense stands of cordgrass or occasionally in dense pickleweed. On rare occasions, they have also been found in freshwater reeds. Tall grass allows the birds to hide, as they pull leaves and stems over their nests. Tall grasses also allow the nests to ride up and down on their stems, enabling the nests to float at high tide. The birds eat invertebrates, mussels and such, although they will eat a variety of other foods when their main foods are unavailable.1
One thing I tell folks about the Ridgway’s rail is that they were once quite common. As far back as 1889 in San Francisco, there were reports of sportsmen returning from hunts with as many as 200 rails. In five years time, however, by 1894, it was noted that the rails were becoming scarce. Despite this decline, nothing was done to protect the bird until the Federal Migratory Bird Treaty Act of 1913 ended the hunting of the rail. Hunting still continued, albeit in a more restrictive and clandestine manner. By then, though, the crack of a shotgun was no longer the primary threat to this species. The encroachment of civilization posed a more serious threat.2
By 1927 almost the entire northern section of San Francisco Bay, which had been habitat for hundreds, perhaps thousands, of rails, was bereft of the bird. Not one could be found. Dozens of other areas that had been known to be home to the bird had been turned into roads, farms, factories, and towns. The area that had been open, coastal wetlands was now known as the town of Hayward, which “throb[bed] with human life and activity.”3 Industrialization and urbanization plagued the coast of California farther south as well. Los Angeles and San Diego were on their way to becoming the second and eighth largest cities in the United States, respectively, and both urbanized their coastlines. It is uncertain exactly how much of southern California’s wetlands have been lost, but estimates vary from 75 to 95 percent.4 If all of our cars and shopping malls weren’t enough, the rails also fall victim to two introduced predators, the red fox and our domestic house cats.5
Ridgway’s rails are sedentary and not prone to move from marsh to marsh. Even over several years, a rail will not move her nesting site more than 400 yards from her first nest. In one study, 55 rails were observed over a three-year period. At the end of the observation, no rail had moved its nesting site more than 70 yards from where it was first sited.6
Because they tend not to move around and because we have paved over so much of their habitat, rails in one marsh tend to stay in that marsh. These isolated populations will thus have little or no breeding with birds from outside their marsh, leading to what is known as genetic bottlenecking. Genetic bottlenecking is the equivalent of people marrying their cousins. Around 20 years ago, research indicated that rails were starting to suffer from this bottlenecking.7
In 1998, the Living Coast Discovery Center (then known as the Chula Vista Nature Center), the zoo where I work, in partnership with SeaWorld San Diego, started a captive breeding program for the Ridgway’s rail.8 Rails from different marshes are brought into a breeding facility just west of the Discovery Center. Once chicks are old enough, they are released to the wild. Dozens and dozens of rails have been bred this way
The breeding program can take some credit for the success of the rail. In 1980 an annual census of the Ridgway’s rail was initiated and sponsored by the California Department of Fish and Game.9 Based on these census records, the population of Ridgway’s rails has gone from a low of 163 nesting pairs in 1989 to a high of 646 nesting pairs in 2016. If this trend continues, the population of the rail may soon reach the target of 800 nesting pairs believed to be the level at which the bird can be self-sustaining.10
News of the week
The New River Conservancy raised $1 million to buy a 174 acre forest in Virginia, ensuring that this area and more than a half mile of riverfront remain protected. In prepping hiking trails, a rare flower was discovered on the newly acquired property.
Two of Rewilding Europe’s projects, the Affric Highlands in Scotland and the Danube Delta in Ukraine, Romania, and Moldova, have been recognized as role models of restoration through their involvement with UN “flagship” initiatives.
The Frankfurt Zoological Society announced on Tuesday that the total number of saiga antelope in Kazakhstan has risen to around 1,318,000 individuals, the highest number of these mammals for the first time in 30 years. The news is not all good. The Kazakh government has allowed for the culling of 80,000 of these creatures in the eastern part of the country because farmers complain that they damage crops and pastures. This migrating animal once ranged from the Hungarian plains to China, but is now found largely in Kazakhstan, with a few populations in Mongolia, Uzbekistan, and Russia.
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U.S. Fish and Wildlife Service. 1985. Recovery plan for the light-footed clapper rail. U.S. Fish and Wildlife Service, Portland, OR. 121 pp.
DeGroot, D.S. 1927. The California clapper rail: Its nesting habits, enemies and habitat. The Condor. Nov-Dec: 259-270.
Southern California Wetlands Recovery Project. 2002. Wetlands Recovery Project Regional Strategy, pp. 1-14
Massey B.W. et al. 1984. Nesting habitat of the light-footed clapper rail in Southern California. Journal of Field Ornithology, Vol. 55 no. 1pp. 67-80.
Zembal, R. et al. 1989. Movements and activity patterns of the light-footed clapper rail. Journal of Wildlife Management. Jan: 39-42.
Nusser J. A. et al. 1996. RAPD analysis reveals low genetic variability in the endangered light-footed clapper rail. Molecular Ecology. Aug: pp. 463-472.
Zembal, R., Hoffman, S.M. 2003. Light-footed clapper rail management, study, and translocation. Contract Report to the Calif. Dept. of Fish and Game. Wildlife Management Div., Nongame Bird and Mammal Section Rep.
Zembal, R. et al. 2006. Status and distribution of the light-footed clapper rail in California. California Dept. of Fish and Game, South Coast Region, Sensitive Bird and Mammal Monitoring Program.
Zembal, R., Hoffman, S.M. 2003.